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  • Thread starter Watson A.Name - \Watt Sun, the Dark Remover\
  • Start date
W

Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
Seems to be a pent-up demand for those ol' timers, that just can't seem
to be quenched. Always someone who's willing to pay exhorbitant prices
for the nearly useless critters. There were three up for bid this week
on Ebay, starting at $15 and buy it now for $30. Last I checked, they
were all spoken for. Unfortunately I had to delete them from my items
i'm watching and I don't have the item numbers. But the picture showed
them sticking out of a DMM that had the transistor checker and the DMM
read somethig like 77 for the gain, so they were apparently working.
But they all looked like they had short leads, so presumably they were
all pulls or from an experimenter's junque box. Who know what kind of
abuse they had been subjected to?

I still have a datasheet for the 2N107, which was GE's answer to the
CK722. I don't think it was ever as popular, and I don't remember what
the price was or which was cheaper. But according to the GE manual, 4th
Ed., the 2N107 and its NPN sister the 2N170 were rated for Vce= -12V,
IC= 10mA and 50mW (107) and 6V, 20mA and 25mW (170). I don't think the
CK722 was much better. Neither of my two substitution manuals from the
early '60s has the CK722, so I don't have an authoritative source. If
someone has a datasheet or other reference for the CK722, please post
it. Thanks.


--
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A

Al

Jan 1, 1970
0
"Watson A.Name - \"Watt Sun, the Dark Remover\""
Seems to be a pent-up demand for those ol' timers, that just can't seem
to be quenched. Always someone who's willing to pay exhorbitant prices
for the nearly useless critters. There were three up for bid this week
on Ebay, starting at $15 and buy it now for $30. Last I checked, they
were all spoken for. Unfortunately I had to delete them from my items
i'm watching and I don't have the item numbers. But the picture showed
them sticking out of a DMM that had the transistor checker and the DMM
read somethig like 77 for the gain, so they were apparently working.
But they all looked like they had short leads, so presumably they were
all pulls or from an experimenter's junque box. Who know what kind of
abuse they had been subjected to?

I still have a datasheet for the 2N107, which was GE's answer to the
CK722. I don't think it was ever as popular, and I don't remember what
the price was or which was cheaper. But according to the GE manual, 4th
Ed., the 2N107 and its NPN sister the 2N170 were rated for Vce= -12V,
IC= 10mA and 50mW (107) and 6V, 20mA and 25mW (170). I don't think the
CK722 was much better. Neither of my two substitution manuals from the
early '60s has the CK722, so I don't have an authoritative source. If
someone has a datasheet or other reference for the CK722, please post
it. Thanks.

CK722

PDmax = 4 milliwatt
BV(cbo) = 22V
Ic max = 10mA
hfe = 30 (test condition unknown)

Extracted from the 1987 D.A.T.A.Book edition 57

I have a few. Why do I want them? Nostalgia! I wish I still had the
super regen AM radio I built with my CK722 and CK768 in the 50's. If I
could find a copy of the schematic, I would try to duplicate it. I still
have some AM loopsticks from the 50's. Jeez, do I have a lot of junk in
my basement!

Al
 
H

Henry Kolesnik

Jan 1, 1970
0
After my first real summer job in 1955 working on a CNR steel relay gang in
BC I stopped in Edmonton and bought two CK722s and a Weller soldering gun.
I still have the gun and it works great. IIRC the two CK722s cost more than
the gun. When I got home I started building an audio amp for my xtal set
and one of the leads just broke off right at the case and I didn't
mishandle it. I was finally able to a tack a lead back on. I then mounted
the transistors on a separate pieces of wood and soldered the leads to
fahenstock clips. Those 2 are long gone but I did find one in a junk box at
a hamfest for free. I'm still a little hesitant to put it to use for fear a
lead might break off. I've heard that germanium transistors don't age well
and some kind of migration degrades their specs.
 
W

Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
Henry Kolesnik said:
After my first real summer job in 1955 working on a CNR steel relay gang in
BC I stopped in Edmonton and bought two CK722s and a Weller soldering gun.
I still have the gun and it works great. IIRC the two CK722s cost more than
the gun. When I got home I started building an audio amp for my xtal set
and one of the leads just broke off right at the case and I didn't
mishandle it. I was finally able to a tack a lead back on. I then mounted
the transistors on a separate pieces of wood and soldered the leads to
fahenstock clips. Those 2 are long gone but I did find one in a junk box at
a hamfest for free. I'm still a little hesitant to put it to use for fear a
lead might break off. I've heard that germanium transistors don't age well
and some kind of migration degrades their specs.

After awhile the makers determined that since germanium couldn't be
passivated like silicon, it was a Really Good Idea to put them in a
hermetically sealed package, such as the TO-5, and later occasionally
TO-18. But apparently the Raytheon manufacturing process was clean
enough to allow those CKs to be in a package sealed with epoxy or some
plastic, and still not get contaminated over the years. But a lot of
the CKs were knockoffs from somewhere else or else rejects, and were
destined to suffer some degradation over time. Their performance is so
mediocre that they really aren't worth anything today except for
collecible value.

And they certainly seem to be in demand by collectors. I should put the
half dozen or so that I have up for sale on Ebay, but I don't really
need the money that bad. I think I would be better off liquidating the
stam collection that I have from when I was a kid; it could bring a few
thou. But the prices of commemoratives don't seem to have gone up by
more than 10 to 25% of their face value. So I don't think I'd be making
minimum wage. :-(
 
J

Jon Elson

Jan 1, 1970
0
Henry said:
After my first real summer job in 1955 working on a CNR steel relay gang in
BC I stopped in Edmonton and bought two CK722s and a Weller soldering gun.
I still have the gun and it works great. IIRC the two CK722s cost more than
the gun. When I got home I started building an audio amp for my xtal set
and one of the leads just broke off right at the case and I didn't
mishandle it. I was finally able to a tack a lead back on. I then mounted
the transistors on a separate pieces of wood and soldered the leads to
fahenstock clips. Those 2 are long gone but I did find one in a junk box at
a hamfest for free. I'm still a little hesitant to put it to use for fear a
lead might break off. I've heard that germanium transistors don't age well
and some kind of migration degrades their specs.
Hmmm, could be. I overhauled an HP synthesizer from the 1960's that
must have had
100 Germainum transistors in it. There must have been 10 dead ones. I
found one
of the Motorola UHF silicon transistors (I forget, either MPSH10 or MPSH81)
seemed to be a drop-in replacement for them. I did get it working, but
it took way too
much time. (This unit was definitely a decade later than the CK722
vintage transistors.)

Jon
 
J

Jorgen Lund-Nielsen

Jan 1, 1970
0
Jon said:
Hmmm, could be. I overhauled an HP synthesizer from the 1960's that
must have had
100 Germainum transistors in it. There must have been 10 dead ones. I
found one
of the Motorola UHF silicon transistors (I forget, either MPSH10 or MPSH81)
seemed to be a drop-in replacement for them. I did get it working, but
it took way too
much time. (This unit was definitely a decade later than the CK722
vintage transistors.)

Jon

Recently, i have repaired an old frequency divider (hp 5260A)
from the mid/end of the sixties, in which a lot of
silicon transistors (2N3904) all has lost their emitters (went open
circuit, only remained a diode function from base to collector)...
interestingly, nearly all transistors that i have found to be defectife
due to aging process (not due to a suddenly hefty overload) went gone
open emitter...

Jorgen
dj0ud
 
W

Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
Jon Elson said:
Hmmm, could be. I overhauled an HP synthesizer from the 1960's that
must have had
100 Germainum transistors in it. There must have been 10 dead ones. I
found one
of the Motorola UHF silicon transistors (I forget, either MPSH10 or MPSH81)
seemed to be a drop-in replacement for them. I did get it working, but
it took way too
much time. (This unit was definitely a decade later than the CK722
vintage transistors.)

Jon

Well, let us know which model that might be so we can avoid that one in
the future. [:)
 
J

Jorgen Lund-Nielsen

Jan 1, 1970
0
Watson said:
Henry Kolesnik wrote:

gang in

more than
set

mounted

to

box at

fear a

age well
Hmmm, could be. I overhauled an HP synthesizer from the 1960's that
must have had
100 Germainum transistors in it. There must have been 10 dead ones.
I

found one
of the Motorola UHF silicon transistors (I forget, either MPSH10 or
MPSH81)

seemed to be a drop-in replacement for them. I did get it working,
but

it took way too
much time. (This unit was definitely a decade later than the CK722
vintage transistors.)

Jon


Well, let us know which model that might be so we can avoid that one in
the future. [:)


I expect the synthesizecould be the 5100's series
(5100A, 5105A, 5110A Synth. Driver) which in fact contains a whole lot
of old germaniums. And step recovery diodes which
also are made of unobtainium ;-) (similarly seldom as tunnel diodes)

Jorgen
 

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